Method for manufacturing semiconductor device and semiconductor memory device

ABSTRACT

A method for manufacturing a semiconductor device includes forming a sacrificial member on a foundation layer, the sacrificial member extending in a first direction along a front surface of the foundation layer; forming a line and space pattern including a plurality of structures on the foundation layer and the sacrificial member, the structures extending along the front surface of the foundation layer in a second direction crossing the first direction; and forming communication passages between the foundation layer and the structures by selectively removing the sacrificial member via spaces between the structures, the spaces being in communication with each other through the communication passages.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2018-042021, filed on Mar. 8, 2018; theentire contents of which are incorporated herein by reference.

FIELD

Embodiments relate to a method for manufacturing a semiconductor device,and a semiconductor memory device.

BACKGROUND

In a manufacturing process of a semiconductor device, processingsolution is supplied to a wafer surface during a wet etching process anda surface cleaning process, and then, the wafer surface is processed tobe dried. When the line and space pattern with a large aspect ratio isformed on the wafer surface, for example, there may be a case where theline and space pattern is collapsed due to Laplace pressure induced bythe processing solution remaining therein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view schematically showing a semiconductormemory device according to an embodiment;

FIG. 2 is a schematic plan view showing a top surface of thesemiconductor memory device according to the embodiment;

FIGS. 3A and 3B are schematic cross-sectional views showing thesemiconductor memory device according to the embodiment;

FIGS. 4A to 8B are schematic views showing a manufacturing processes ofthe semiconductor memory device according to the embodiment;

FIGS. 9A and 9B are schematic views showing a manufacturing method ofthe semiconductor memory device according to the embodiment; and

FIGS. 10A and 10B are schematic views showing a manufacturing method ofthe semiconductor memory device according to a variation of theembodiment.

DETAILED DESCRIPTION

According to one embodiment, a method for manufacturing a semiconductordevice includes forming a sacrificial member on a foundation layer, thesacrificial member extending in a first direction along a front surfaceof the foundation layer; forming a line and space pattern including aplurality of structures on the foundation layer and the sacrificialmember, the structures extending along the front surface of thefoundation layer in a second direction crossing the first direction; andforming communication passages between the foundation layer and thestructures by selectively removing the sacrificial member via spacesbetween the structures, the spaces being in communication with eachother through the communication passages.

Embodiments will now be described with reference to the drawings. Thesame portions inside the drawings are marked with the same numerals; adetailed description is omitted as appropriate; and the differentportions are described. The drawings are schematic or conceptual; andthe relationships between the thicknesses and widths of portions, theproportions of sizes between portions, etc., are not necessarily thesame as the actual values thereof. The dimensions and/or the proportionsmay be illustrated differently between the drawings, even in the casewhere the same portion is illustrated.

There are cases where the dispositions of the components are describedusing the directions of XYZ axes shown in the drawings. The X-axis, theY-axis, and the Z-axis are orthogonal to each other. Hereinbelow, thedirections of the X-axis, the Y-axis, and the Z-axis are described as anX-direction, a Y-direction, and a Z-direction. Also, there are caseswhere the Z-direction is described as upward and the direction oppositeto the Z-direction is described as downward.

FIG. 1 is a perspective view schematically showing a semiconductormemory device 1 according to an embodiment. The semiconductor memorydevice 1 is, for example, a NAND type non-volatile memory deviceincluding memory cells three-dimensionally disposed. In FIG. 1,insulating films are omitted, which electrically insulate the componentsshown therein from each other.

The semiconductor memory device 1 includes multiple electrode layers(hereinafter, a selection gate SGS, word lines WL, and a selection gateSGD) stacked above a source layer SL, and multiple columnar bodies CL.

The columnar bodies CL extends through the selection gate SGS, the wordlines WL, and the selection gate SGD in the stacking direction (i.e.,Z-direction). The columnar body CL includes a semiconductor layer 30extending in the Z-direction (see FIG. 3), and is electrically connectedto a bit line BL through a connection plug CV. That is, the columnarbody CL is electrically connected to the source layer SL.

As shown in FIG. 1, each end portion of the selection gate SGS, the wordlines WL, and the selection gate SGD is provided with a stair shape. Theselection gate SGS, the word lines WL, and the selection gate SGD areconnected to interconnections GL in the upper layer through contactplugs CC and connection plugs CY connected to end portions of theelection gate SGS, the word lines WL, and the selection gate SGD,respectively.

The semiconductor memory device 1 further includes columnar supportbodies SCL, and embedded members CM. The columnar support bodies SCLeach extends in the Z-direction through at least one of the selectiongate SGS, the word lines WL, and the selection gate SGD. The columnarsupport bodies SCL each include, for example, insulator such as siliconoxide. The embedded members CM are provided between the source layer SLand the selection gate SGS, and extend in the Y-direction along asurface of the source layer SL. The embedded members CM each include,for example, a material same as the materials of the selection gate SGS,the word lines WL, and the selection gate SGD.

FIG. 2 is a schematic plan view showing a top surface of thesemiconductor memory device 1 according to the embodiment. Thesemiconductor memory device 1 includes multiple stacked bodies 10, forexample, arranged in the Y-direction. The stacked bodies 10 each includea selection gate SGS, word lines WL, and a selection gate SGD stacked inthe Z-direction.

As shown in FIG. 2, an outer periphery of the stacked bodies 10 isdefined by a slit ST. The slit ST has a depth from a level of topsurfaces of the stacked bodies 10 to the source layer SL. The slit ST isfilled with an insulating film such as a silicon oxide film, whichelectrically insulates the adjacent stacked bodies 10 (see FIG. 8B) fromeach other.

The stacked bodies 10 each extend, for example, in the X-direction, andinclude memory cell regions MCR1, MCR2, hook-up regions HUR1, HUR2, anda tap region TPR. The memory cell regions MCR1, MCR2, the hook-upregions HUR1, HUR2, and the tap region TPR are arranged in theX-direction.

The hook-up regions HUR1 and HUR2 are placed at both ends of eachstacked body 10, respectively. The memory cell regions MCR1 and MCR2 areprovided between the hook-up regions HUR1 and HUR2. The tap region TPRis placed between the memory regions MCR1 and MCR2.

The multiple columnar bodies CL are provided in the memory cell regionsMCR1 and MCR2, and the bit lines BL are placed above the memory cellregions MCR1 and MCR2. The contact plugs CC are provided in the hook-upregions HUR1 and HUR2 and connected to the end portions of the selectiongate SGS, the word lines WL and the selection gate SGD formed in thestaircase. The columnar support bodies SCL are provided in the hook-upregions HUR1 and HUR2.

A contact plug is provided in the tap region TPR, for example, toelectrically connect the source layer SL and an interconnection in theupper layer. Another contact plug is also provided in the tap region TPRto electrically connect other interconnection in the upper layer and acircuit provided between the source layer SL and a substrate (notshown). Furthermore, columnar support bodies SCL are also provided inthe tap region TPR.

As shown in FIG. 2, the embedded members CM are placed in the hook-upregions HUR1, HUR2 and the tap region TPR, respectively. The embeddedmembers CM are provided in a bottom portion of the stacked bodies 10,and the both ends thereof contact the insulating film provided in theslit ST.

When the embedded members CM include, for example, metal and placed inthe memory cell region MCR1 or MCR2, the embedded members CM mayinterfere with the connection of the source layer SL and thesemiconductor layers included in the columnar bodies CL, and causeshort-circuit between the columnar bodies. In contrast, the contactplugs in the hook-up regions HUR1, HUR2 and the tap region TPR are notprovided in high density comparing with the columnar bodies CL. Thereby,it is possible to ensure the space margin enough to place the embeddedmembers CM between the contact plugs. Since the columnar support bodiesSCL are insulator, short-circuit is not caused therebetween by theembedded members CM. Thus, the embedded members CM are placed in thehook-up regions HUR1, HUR2 and the tap region TPR, respectively.

FIGS. 3A and 3B are schematic cross-sectional views showing thesemiconductor memory device 1 according to the embodiment. FIG. 3A is aschematic view showing a cross-sectional structure of the columnar bodyCL. FIG. 3B is a schematic view showing a cross section along line A-Ashown in FIG. 3A, and shows the structure of the memory cell MC.

As shown in FIG. 3A, a columnar body CL extends in the Z-directionthrough the stacked structure on the source layer SL of insulating films13, 15, the selection gate SGS, the word lines WL and the selection gateSGD. The insulating films 15 are placed between the selection gate SGSand the word lines WL, between the adjacent word lines WL, and betweenthe word lines WL and the selection gate SGD, respectively. Aninsulating film 17 is provided between the uppermost insulating film 15and the bit line BL.

The columnar body CL includes a memory film MF, the semiconductor linesWL, and insulative core 35. The insulative core 35 is, for example,silicon oxide, and extends in the Z-direction. The semiconductor layer30 is provided so as to surround the insulative core 35, and isconnected to the source layer SL at the bottom end. The semiconductorlayer 30 is connected to the connection plug CV at the top end. Thesemiconductor layer 30 is, for example, a polysilicon layer.

The memory film MF is provided to cover a side surface of thesemiconductor layer 30, and extends in the Z-direction along thesemiconductor layer 30. The memory film MF has multilayer structureincluding, for example, a blocking insulator film 23, a charge storagefilm 25 and a tunneling insulator film 27.

The blocking insulator film 23, the charge storage film 25 and thetunneling insulator film 27 are stacked in a direction from a word lineWL toward the insulative core 35. The blocking insulator film 23 and thetunneling insulator film 27 are, for example, silicon oxide films. Thecharge storage film 25 is, for example, a silicon nitride film. Theblocking insulator film 23 may have, for example, a multilayer structureincluding metal oxide such as an aluminum oxide.

The memory cell MC shown in FIG. 3B is provided in a portion where thecolumnar body CL crosses the word line WL. The memory film MF ispositioned between the semiconductor layer 30 and the word line WL, andis provided so as to surround the semiconductor layer 30. A portion ofthe memory film MF positioned between the semiconductor layer 30 and theword line WL functions as the memory portion of the memory cell MC. Thesemiconductor layer 30 functions as a channel of the memory cell MC, andthe word line WL functions as a control gate of the memory cell MC.

The memory film MF may include the charge storage films 25 separated oneanother in an extending direction of the columnar body CL (i.e.,Z-direction). The charge storage films 25 each are positioned betweenthe semiconductor layer 30 and the word line WL. In such a case, thememory cell MC may have a structure in which the charge storage films 25are conductive, and each function as a floating gate.

Next, a manufacturing method of the semiconductor memory device 1according to the embodiment will be described with reference to FIGS. 4Ato 8B. FIGS. 4A to 8B are schematic views sequentially showingmanufacturing processes of the semiconductor memory device 1.

FIG. 4A is a schematic view showing a cross section of the source layer37 and an insulating film 37 and sacrificial members 40 formed on thesource layer SL. FIG. 4B is a plan view showing a top surface of theinsulating film 37. The source layer SL is, for example, a conductivepoly-silicon layer, and is provided above a substrate (not shown) via aninterlayer insulating film.

As shown in FIGS. 4A and 4B, the line-shaped sacrificial members 40extending in the Y-direction are provided on the insulating film 37. Theinsulating film 37 is, for example, a silicon oxide film. Thesacrificial members 40 are, for example, undoped polysilicon.

A thickness T_(SC) in the Z-direction and a width W_(SC) in theX-direction of the sacrificial members 40 are for example, not less than14 nanometers (nm). The thickness T_(SC) and the width W_(SC) arepreferably not less than 20 nm, and more preferably not less than 30 nm.

As shown in FIG. 5A, the insulating film 13 is formed on the insulatingfilm 37. The insulating film 13 is formed so as to cover the sacrificialmembers 40. Furthermore, sacrificial films 45 and the insulating films15 are stacked alternately on the insulating film 13. The number of thesacrificial films 45 stacked is, for example, the same as the number ofthe selection gate SGS, the word lines WL and the selection gate SGD.The insulating films 13 and 15 are, for example, silicon oxide films.The sacrificial films 45 are, for example, silicon nitride films.

As shown in FIG. 5B, end portions of the insulating films 15 and thesacrificial films 45 are formed into the staircase. The insulating films15 and the sacrificial films 45 are sequentially removed, for example,while the edge of the etching mask (not shown) is set back step by step.

As shown in FIG. 6A, an insulating film 55 are formed to cover endportions of the insulating films 15 and the sacrificial films 45. Theinsulating film 55 is formed so that the top surface thereof ispositioned at a level same as a top surface of the uppermost insulatingfilm 15. The insulating film 55 is, for example, a silicon oxide film.

As shown in FIG. 6B, the columnar bodies CL and the columnar supportbodies SCL are formed so as to extend through the sacrificial films 45.The columnar bodies CL are formed at positions separated from thesacrificial members 40, for example, with spacing at least broader thanthe displacement in the photo-alignment. Thereby, it is possible toavoid the interference between the columnar bodies CL and thesacrificial members 40. On the other hand, it is possible to place thecolumnar support body SCL in the vicinity of the sacrificial members 40.

As shown in FIG. 7A, after an insulating film 17 covering the columnarbodies CL and the columnar supports SCL are formed, the slit ST isformed by using a mask layer 63. The slit ST is formed using, forexample, anisotropic RIE (Reactive Ion Etching) so as to have a depthfrom a top surface of the insulating film 17 to the source layer SL.

As shown in FIG. 7B, communication passages CP are formed between thelowermost sacrificial film 45 and the source layer SL. FIG. 7B and thefollowing FIGS. 8A and 8B are schematic views showing cross sectionalong the line B-B shown in FIG. 7A.

The communication passages CP are formed by selectively removing thesacrificial members 40 through the slit ST. The communication passagesCP are cavities formed by selectively removing the sacrificial members40.

For example, etching solution is supplied through the slit ST so thatpoly-silicon is selectively etched without etching the silicon oxidefilm and the silicon nitride film. Moreover, the etching solution isused in the etching of the sacrificial members 40 so that an etchingrate of the undoped poly-silicon is larger than an etching rate of theconductive poly-silicon including impurities doped therein.

As shown in FIG. 8A, after the mask layer 63 is removed, the sacrificialfilms 45 are selectively removed through the slit ST, and spaces 45S areformed between the insulating films 15. For example, the sacrificialfilms 45 that are the silicon nitride films are selectively removed bysupplying hot phosphoric acid via the slit ST.

As shown in FIG. 8B, after a metal layer is formed inside the spaces 45Sthrough the slit ST, an insulating film 65 is formed so as to fill theslit ST. The selection gate SGS, the word lines WL and the selectiongate SGD are formed inside the spaces 45S. At this time, the metal layeris also deposited in the communication passage CP, and the embeddedmembers CM are formed. The embedded members CM are formed such that theend surfaces thereof contact the insulating film 65.

Then, the contact plugs CC and the upper layer including theinterconnections GL, the bit lines BL and the like are formed tocomplete the semiconductor memory device 1 (see FIG. 1).

FIGS. 9A and 9B are schematic views showing a manufacturing method ofthe semiconductor device according to the embodiment. FIG. 9A is aschematic view showing a step of removing the mask layer 63 in themanufacturing process shown in FIG. 7B. FIG. 9B is a schematic viewshowing the same step of a manufacturing method in which thecommunication passages CP are not provided.

The mask layer 63 is, for example, a resist film, and is removed byusing stripping solution or acid solution. Through the removing process,a part of the stripping solution or the acid solution, or a part of acleaning solution replacing the stripping solution or acid solution mayremain inside the slit ST. In the example shown in FIG. 9A, portions ofthe slit ST are connected by the communication passage CP. Thereby, theprocessing solution PL remains inside the portions of the slit ST withsubstantially the same amount between the stacked bodies 10 f. On thecontrary, since the communication passage CP is not formed in theexample shown in FIG. 9B, various amounts of the processing solution PLremain in the portions of the slit ST between the stacked bodies 10 g.Thus, Laplace pressure is induced by the difference of interfacialtension due to the processing solution PL remaining in the portions ofthe slit ST, and the stacked bodies 10 g including the insulating films15 and the sacrificial films 45 are deflected, for example. When theaspect ratio (T_(SB)/W_(SB)) of the stacked bodies 10 g is large, thedeflection amount becomes large, and the stacked bodies may becollapsed.

In the manufacturing method of the semiconductor device according to theembodiment, the processing solution PL remains uniformly in the slit STby the communication passages CP, and thus, it is possible to suppressthe Laplace pressure. Thereby, the structure having a high aspect ratiocan be avoided to be collapsed in a wet process in the manufacturingprocess of the semiconductor device. Accordingly, it is possible toimprove the manufacturing yield of the semiconductor device.

The communication passage CP has a size in cross section thereof, forexample, not less than 30 nm in the width and height so that theprocessing solution flows smoothly, and remains uniformly in theportions of the slit ST. The shape of the cross section of thecommunication passage CP is not limited to a rectangular, and may becircular. In such a case, a radius of the cross sectional shape may beenough to be not less than 15 nm, for example. Higher density of thecommunication passages CP in the foundation layer makes the strengthlower in the structure formed thereon. Preferably, the communicationpassages CP are appropriately disposed at the center and both ends of astacked body as illustrated in FIG. 2.

In the semiconductor memory device 1 shown in FIG. 1, the number of theword lines stacked is preferably increased to enlarge the memorycapacity. That is, the number of the sacrificial films 45 stackedbecomes large. The aspect ratio of the stacked body becomes large, andthus, the stacked body may be collapsed easily. Accordingly, themanufacturing method according to the embodiment may improve themanufacturing yield of the semiconductor memory device 1.

FIGS. 10A and 10B are schematic views showing a manufacturing method ofthe semiconductor memory device 1 according to a variation of theembodiment. FIG. 10A is a schematic view showing the cross section ofsacrificial members 70 formed on the source layer SL and an insulatingfilm 37 formed on the sacrificial members 70. FIG. 10B is a plan viewshowing a top surface of the insulating film 37.

As shown in FIG. 10A, the sacrificial members 70 are formed in groovesthat are formed in the source layer SL. As shown in FIG. 10B, thesacrificial members 70 are formed into a line shape extending in theY-direction. The sacrificial members 70 include, for example, a metal orundoped polysilicon.

Also in the example, the semiconductor memory device 1 is formed throughthe manufacturing processes shown in FIG. 5A to FIG. 8B. By selectivelyremoving the sacrificial members 70, the communication passages CP areformed as the grooves in the source layer SL. Thereby, the processingsolution uniformly remains in the slit ST through the wet process, andit is possible to suppress Laplace pressure.

In the example, the sacrificial members 70 are provided in the groovesof the source layer SL. Thus, the top surface of the source layer SL ismaintained to be flat, and it is possible to reduce the influence of thesacrificial members 70 on the respective layers stacked thereabove.Thereby, the sacrificial members 70 may have a size larger in the crosssection, i.e., may be formed with the larger cross section.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the invention.

What is claimed is:
 1. A semiconductor memory device, comprising: aconductive layer; a plurality of electrode layers stacked above theconductive layer, the electrode layers extending in a first directionalong a front surface of the conductive layer; a columnar body extendingthrough the electrode layers in a stacking direction of the electrodelayers, the columnar body including a semiconductor layer extending inthe stacking direction; a first insulating film covering first sidesurfaces of the electrode layers; a second insulating film coveringsecond side surfaces of the electrode layers other than the first sidesurfaces, the electrode layers and the columnar body being providedbetween the first and second insulating films; and an embedded memberprovided between the conductive layer and a lowermost electrode layer ofthe electrode layers, the embedded member extending in a seconddirection along the front surface of the conductive layer and crossingthe first direction, and the embedded member having a first endcontacting the first insulating film and a second end contacting thesecond insulating film.
 2. The device according to claim 1, wherein theembedded member includes a material that is the same as a material ofthe electrode layers.
 3. The device according to claim 1, furthercomprising: a columnar support body extending through at least oneelectrode layer of the electrode layers, wherein: the at least oneelectrode layer includes a first region and a second region, thecolumnar body extends through the first region, the columnar supportbody extends through the second region, and the embedded member ispositioned between the second region and the conductive layer.
 4. Thedevice according to claim 1, wherein: the electrode layers are providedin a stacked body having first and second side surfaces, the second sidesurface is positioned on a side opposite to the first side surface, thefirst insulating film is provided on the first side surface, and thesecond insulating film is provided on the second side surface.
 5. Thedevice according to claim 1, wherein the embedded member is positionedinside a groove provided in the conductive layer.
 6. The deviceaccording to claim 1, comprising: a plurality of stacked bodies providedon the conductive layer, the plurality of stacked bodies being arrangedin the second direction, and each of the stacked bodies including theelectrode layers and the embedded member, wherein the embedded membersof the stacked bodies are arranged in the second direction.
 7. Thedevice according to claim 1, further comprising: an interconnectionprovided above the electrode layers, and extending in the seconddirection, wherein: the semiconductor layer is electrically connected tothe interconnection, and no interconnection electrically connected tothe semiconductor layer is placed above the embedded member.
 8. Thedevice according to claim 1, wherein the columnar body includes a chargestorage film positioned between the semiconductor layer and theelectrode layers.
 9. The device according to claim 1, wherein: thecolumnar body includes a plurality of charge storage portions positionedbetween the semiconductor layer and the electrode layers, and the chargestorage portions are separated from each other in the stackingdirection, and are placed between the semiconductor layer and theelectrode layers, respectively.
 10. The device according to claim 9,wherein the charge storage portions are conductive.
 11. The deviceaccording to claim 1, wherein the columnar body includes an insulatorextending in the stacking direction, the insulator being positionedinside the semiconductor layer.
 12. The device according to claim 1,wherein: the columnar body contacts the conductive layer, and thesemiconductor layer is connected to the conductive layer.
 13. The deviceaccording to claim 1, wherein the columnar body is provided apart fromthe first and second insulating films.
 14. The device according to claim1, wherein the embedded member is provided between the first and secondinsulating films.
 15. The device according to claim 1, wherein each ofthe first and second insulating films comprises a planar body extendingin the first direction along the electrode layers.